Method and System for Utilizing Reduced Functionality Processing Channels in a GNSS Receiver

ABSTRACT

A global navigation satellite system (GNSS) receiver comprising one or more regular channel circuits and one or more sniff channel circuits may be operable, utilizing the sniff channel circuits, to monitor power levels of currently visible GNSS satellites which are not being utilized by the regular channel circuits. An alternative GNSS satellite from the currently monitored GNSS satellites may be selected by the GNSS receiver based on the monitored power levels. GNSS signals received from the selected alternative GNSS satellite may be processed by a regular channel circuit. The GNSS receiver may be operable to detect, for example, signal-to-noise ratios (SNRs) or carrier-to-noise density ratios (C/N0s) of the currently visible GNSS satellites utilizing the sniff channel circuits. The sniff channel circuits may not be utilized to generate GNSS measurements so that functionality of each of the sniff channel circuits may be reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This application is a continuation of co-pending U.S. patent applicationSer. No. 12/702,786 filed Jul. 9, 2010, which is hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to communication systems.More specifically, certain embodiments of the invention relate to amethod and system for utilizing reduced functionality processingchannels in a GNSS receiver.

BACKGROUND OF THE INVENTION

A global navigation satellite system (GNSS) utilizes an earth-orbitingconstellation of a plurality of satellites each broadcasting GNSSsignals which indicates its precise location and ranging information.From particular locations on or near the earth, GNSS receivers maydetect valid GNSS signals and take various GNSS measurements such aspseudorange, carrier phase, and/or Doppler to calculate navigationinformation or solution such as GNSS receiver position, velocity, andtime. The American global positioning system (GPS), the Russian globalorbiting navigation satellite system (GLONASS), the European Galileopositioning system and the Chinese Compass navigation system areexamples of GNSSs.

A GNSS receiver is often described by its number of channels. In a GNSSreceiver, a channel is a path for an electronic signal that is reservedfor a specific GNSS satellite and used for various functions. The numberof channels in a GNSS receiver signifies how many GNSS satellites theGNSS receiver can monitor simultaneously. Originally limited to four orfive, the number of channels in, a GNSS receiver has progressivelyincreased over the years so that a GNSS receiver may typically have alarge number of channels for processing signals from many GNSSsatellites.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with the present invention as set forth inthe remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method for utilizing reduced functionality processingchannels in a GNSS receiver, substantially as shown in and/or describedin connection with at least one of the figures, as set forth morecompletely in the claims.

Various advantages, aspects and novel features of the present invention,as well as details of an illustrated embodiment thereof, will be morefully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FI block diagram illustrating an exemplary communication operable toprovide utilization of reduced functionality processing channels in aGNSS receiver, in accordance with an embodiment of the invention.

FIG. 2 is a block diagram illustrating an exemplary GNSS receiver thatis operable to utilize reduced functionality processing channels, inaccordance with an embodiment of the invention.

FIG. 3 is a block diagram illustrating an exemplary regular channel andan exemplary sniff channel of the GNSS receiver, in accordance with anembodiment of the invention.

FIG. 4 is a flow chart illustrating exemplary steps for utilizingreduced functionality processing channels in a GNSS receiver, inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention can be found in a method and systemfor utilizing reduced functionality processing channels in a GNSSreceiver. In various embodiments of the invention, a global navigationsatellite system (GNSS) receiver, which comprises one or more regularchannel circuits and one or more sniff channel circuits, may be operableto monitor power levels of currently visible GNSS satellites utilizingone or more of the sniff channel circuits. In this regard, the currentlymonitored visible GNSS satellites are not being utilized by the regularchannel circuits. An alternative GNSS satellite from the currentlymonitored GNSS satellites that are not being utilized may be selected bythe GNSS receiver based on the monitored power levels. GNSS signalsreceived from the selected alternative GNSS satellite may be processedby the GNSS receiver utilizing one of the regular channel circuits. Inthis regard, the GNSS receiver may be operable to detect, for example,signal-to-noise ratios (SNRs) or carrier-to-noise density ratios (C/N0s)of the currently visible GNSS satellites utilizing the sniff channelcircuits. Each of the regular channel circuits may be utilized togenerate GNSS measurements for calculating a navigation solution of theGNSS receiver. Each of the regular channel circuits may comprise aplurality of multi-tap correlators and each of the multi-tap correlatorsmay comprise a delay-locked loop (DLL). An early correlator tap, a latecorrelator tap and the delay-locked loop (DLL) may be utilized by eachof the multi-tap correlators to produce a punctual correlator tap duringa correlation process.

The sniff channel circuits may not be utilized by the GNSS receiver togenerate GNSS measurements so that functionality of each of the sniffchannel circuits may be reduced. In other words, the sniff channelcircuits do not handle all the channel processing that is handled by theregular channel circuits. The sniff channel circuits only handle asubset of the channel processing that is handled by the regular channelcircuits. Each of the sniff channel circuits may comprise a single-tapcorrelator. A navigation solution of the GNSS receiver may be utilizedby the single-tap correlator to produce a punctual correlator tap duringa correlation process.

The GNSS receiver may comprise, for example, a global positioning system(GPS) receiver, a global orbiting navigation satellite system (GLONASS)receiver, a Galileo receiver and/or a Compass receiver.

FIG. 1 is a block diagram illustrating an exemplary communication systemthat is operable to provide utilization of reduced functionalityprocessing channels in a GNSS receiver, in accordance with an embodimentof the invention. Referring to FIG. 1, there is shown a communicationsystem 100. The communication system 100 comprises a plurality of GNSSreceivers 110 of which GNSS receivers 110 a-110 c are illustrated, and aGNSS infrastructure 120. The GNSS infrastructure 120 comprises aplurality of GNSS satellites such as GNSS satellites 120 a through 120c.

The GNSS receiver such as the GNSS receiver 110 a may comprise suitablelogic, circuitry, interfaces and/or code that may be operable to receiveGNSS broadcast signals from a plurality of visible GNSS satellites suchas GNSS satellites 120 a through 120 c in the GNSS infrastructure 120.The GNSS receiver 110 a may comprise, for example, a GPS receiver, aGLONASS receiver, a Galileo receiver and/or a Compass receiver.

The advent of multiple satellite constellations has placed great demandon GNSS receivers 110 to provide a large number of channels forutilizing signals from many GNSS satellites 120. However, it may not benecessary to produce or generate GNSS measurements from all channels.Having so many GNSS measurements could overburden a CPU or basebandprocessor of the GNSS receiver 110 a.

In an exemplary embodiment of the invention, the GNSS receiver 110 a maycomprise one or more regular channel circuits and one or more sniffchannel circuits. The regular channel circuit is a full functionalityprocessing channel circuit while the sniff channel circuit is asimplified and reduced functionality processing channel circuit withrespect to the regular channel circuit. The GNSS receiver 110 a may beoperable to monitor power levels of currently visible GNSS satellitessuch as, for example, the GNSS satellites 120 b, 120 c utilizing thesniff channel circuits, while these monitored GNSS satellites 120 b, 120c are not being utilized by the regular channel circuits. In thisregard, for example, the GNSS receiver 110 a may be operable to detectsignal-to-noise ratios (SNRs) or carrier-to-noise density ratios (C/N0s)of the currently visible GNSS satellites 120 b, 120 c utilizing thesniff channel circuits. The SNR is the ratio of the signal power to thenoise power as measured in dB. The C/N0 is the ratio of the power levelof a signal carrier to the noise power in a 1-Hz bandwidth as measuredin dB-Hz. In instances when the GNSS receiver 110 a loses lock on acurrently utilized GNSS satellite such as, for example, the GNSSsatellite 120 a an alternative GNSS satellite from the currentlymonitored GNSS satellites 120 b, 120 c may be selected by the GNSSreceiver 110 a based on the monitored power levels of the currentlymonitored GNSS satellites 120 b, 120 c. The selected alternative GNSSsatellite such as, for example, the GNSS satellite 120 b may be utilizedby one of the regular channel circuits for processing. Accordingly, theGNSS receiver 110 a may be able to promptly select alternative GNSSsatellites to track.

Each of the regular channel circuits may be utilized to generate GNSSmeasurements for calculating a navigation solution of the GNSS receiver110 a. Each of the sniff channel circuits may not be utilized togenerate GNSS measurements so that functionality of each of the sniffchannel circuits may be reduced.

The GNSS satellite such as the GNSS satellite 120 a may comprisesuitable logic, circuitry, interfaces and/or code that may be operableto provide satellite navigational information or data to various GNSSreceivers on earth such as, for example, the GNSS receiver 110 a through110 c. The GNSS satellite 120 a may be operable to broadcast its ownephemeris periodically, for example, once every 30 seconds. Thebroadcast ephemeris may be utilized to calculate navigation informationor solution such as, for example, position, velocity, and clockinformation of the GNSS receivers 110. The GNSS satellite 120 a may beoperable to update ephemeris, for example, every two hours. Thebroadcast ephemeris may be valid for a limited time period such as, forexample, 2 to 4 hours into the future from the time of broadcast.

In operation, a GNSS receiver such as the GNSS receiver 110 a may beoperable to detect and/or receive GNSS signals from, for example, theGNSS satellites 120 a-120 c. The GNSS receiver 110 a may be operable,utilizing the sniff channel circuits, to monitor power levels of thecurrently visible GNSS satellites 120 b, 120 c while these GNSSsatellites 120 b, 120 c are not being utilized by the regular channelcircuits. An alternative GNSS satellite such as, for example, the GNSSsatellite 120 b from the currently monitored GNSS satellites 120 b, 120c may be selected by the GNSS receiver 110 a based on the monitoredpower levels. The GNSS receiver 110 a may be operable to detect, forexample, signal-to-noise ratios (SNRs) or carrier-to-noise densityratios (C/N0s) of the currently visible GNSS satellites 120 b, 120 cutilizing the sniff channel circuits. Each of regular channel circuitsmay be utilized to generate GNSS measurements for, calculating anavigation solution of the GNSS receiver 110 a. Each of the sniffchannel circuits may not be utilized to generate GNSS measurements, andas a result, the functionality of each of the sniff channel circuits andthe corresponding processing may be reduced.

FIG. 2 is a block diagram illustrating an exemplary GNSS receiver thatis operable to utilize reduced functionality processing channels, inaccordance with an embodiment of the invention. Referring to FIG. 2,there is shown a GNSS receiver 200. The GNSS receiver 200 may comprisean antenna 201, a GNSS front-end 202, a plurality of regular channelcircuits 204, a plurality of sniff channel circuits, a memory 208 and abaseband processor 210.

The antenna 201 may comprise suitable logic, circuitry, interfacesand/or code that may be operable to receive GNSS signals from aplurality of visible or available GNSS satellites such as the GNSSsatellites 120 a through 120 c. The antenna 201 may be operable tocommunicate the received GNSS signals to the GNSS front-end 202 forfurther processing.

The GNSS front-end 202 may comprise suitable logic, circuitry,interfaces and/or code that may be operable to convert the received GNSSsignals to GNSS baseband signals, which may be suitable for furtherprocessing in the regular channel circuits 204, the sniff channelcircuits 206 and or the baseband processor 210.

Each of the regular channel circuits 204 may comprise suitable logic,circuitry, interfaces and or code that may be operable to process orcorrelate GNSS baseband signals from many GNSS satellites 120. Theregular channel circuits 204 are full functionality processing channelcircuits. Each of the regular channel circuits 204 ma generate GNSSmeasurements for calculating a navigation solution of the GNSS receiver200. Each of the regular channel circuits 204 may comprise a pluralityof multi-tap correlators and each of the multi-tap correlators maycomprise a delay-locked loop (DLL). An early correlator tap, a latecorrelator tap and the delay-locked loop (DLL) may be utilized by themulti-tap correlators to produce a punctual correlator tap during acorrelation process.

Each of the sniff channel circuits 206 may comprise suitable logic,circuitry, interfaces and/or code that may be operable to monitor powerlevels of currently visible GNSS satellites 120 b, 120 c. For example,the sniff channel circuits 206 may be operable to detect signal-to-noiseratios (SNRs) or carrier-to-noise density ratios (C/N0s) of thecurrently visible GNSS satellites 120 b, 120 c. The sniff channelcircuits 206 are simplified and reduced functionality processing channelcircuits. Each of the sniff channel circuits 206 may not generate GNSSmeasurements so that functionality of each of the sniff channel circuits206 may be reduced. In other words, the sniff channel circuits 206 onlyhandle a subset of the channel processing that is handled by the regularchannel circuits 204. Each of the sniff channel circuits 206 maycomprise a single-tap correlator. A navigation solution of the GNSSreceiver 200 may be utilized by the single-tap correlator to produce apunctual correlator tap during a correlation process.

The memory 208 may comprise suitable logic, circuitry, interfaces and/orcode that may be operable to store information such as executableinstructions, data and/or database that may be utilized by the regularchannel circuits 204, the sniff channel circuits 206 and the basebandprocessor 210. The memory 208 may comprise RAM, ROM, low latencynonvolatile memory such as flash memory and/or other suitable electronicdata storage.

The baseband processor 210 may comprise suitable logic, circuitry,interfaces and/or code that may be operable to process GNSS basebandsignals from the GNSS front-end 202, the regular channel circuits 204,and/or the sniff channel circuits 206. The baseband processor 210 may beoperable to calculate navigation information or solution for variousnavigation applications.

In an exemplary embodiment of the invention, the baseband processor 210may be operable to select an alternative GNSS satellite such as, forexample, the GNSS satellite 120 b from the currently visible GNSSsatellites 120 b, 120 c based on the power levels of the GNSS satellites120 b, 120 c which may be monitored and detected by the sniff channelcircuits 206.

In operation, the GNSS front-end 202 may be operable to process thereceived GNSS signals via the antenna 201 and convert into GNSS basebandsignals. Each of the regular channel circuits 204 may be operable toprocess or correlate GNSS baseband signals from many GNSS satellites120. Each of the regular channel circuits 204 may generate GNSSmeasurements for calculating a navigation solution of the GNSS receiver200. Each of the regular channel circuits 204 may comprise a pluralityof multi-tap correlators and each of the multi-tap correlators may,comprise a delay-locked loop (DLL). An early correlator tap, a latecorrelator tap and the delay-locked loop (DLL) may be utilized by themulti-tap correlators to produce a punctual correlator tap during acorrelation process. Each of the sniff channel circuits 206 may beoperable to monitor power levels of currently visible GNSS satellites120 b, 120 c such as, for example, the signal-to-noise ratios (SNRs) orthe carrier-to-noise density ratios (C/N0s). Each of the sniff channelcircuits 200 may comprise one single-tap correlator. A navigationsolution of the GNSS receiver 200 may be utilized by the single-tapcorrelator to produce a punctual correlator tap during a correlationprocess. The baseband processor 210 may be operable to calculatenavigation solution for various navigation applications. The basebandprocessor 210 may be operable to select an alternative GNSS satellitesuch as, for example, the GNSS satellite 120 b among the currentlymonitored GNSS satellites 120 b, 120 c based on the power levels of theGNSS satellites 120 b, 120 c which may be monitored and detected by thesniff channel circuits 206. The selected alternative GNSS satellite 120b may be utilized by one of the regular channel circuit 204 forprocessing.

FIG. 3 is a block diagram illustrating an exemplary regular channelcircuit and an exemplary sniff channel circuit of the GNSS receiver, inaccordance with an embodiment of the invention. Referring to FIG. 3,there is shown a regular channel circuit 301 and a sniff channel circuit302. The regular channel circuit 301, which is a full functionalityprocessing channel circuit, may comprise a plurality of multi-tapcorrelators 301 a, 301 b for searching for satellite signals in time.Each of the multi-tap correlators 301 a, 301 b may comprise a DLL suchas the DLL 312 a or the DLL 312 b. The sniff channel circuit 302, whichis a simplified and reduced functionality processing channel circuitwith respect to the regular channel circuit 301, may comprise asingle-tap correlator 320.

The multi-tap correlator such as the multi-tap correlator 310 a maycomprise suitable logic, circuitry, interfaces and/or code that may beoperable to perform correlation function of the regular channel circuit301 for generating GNSS measurements. The multi-tap correlator 310 a mayemploy the DLL 312 a and utilize an early correlator tap and a latecorrelator tap to drive the DLL 312 a for producing a punctualcorrelator tap. The produced punctual correlator tap may be used to lockand/or track a visible GNSS satellite such as, for example, the GNSSsatellite 120 a for generating GNSS measurements.

The single-tap correlator 320 may comprise suitable logic, circuitry,interfaces and/or code that may be operable to perform correlationfunction of the sniff channel circuit 302 for monitoring or detectingpower levels of available GNSS satellites 120. The single-tap correlator320 does not employ a DLL. Instead, the timing location of the singlepunctual correlator tap is guided by a navigation solution of the GNSSreceiver 110 a. The navigation solution provides information such ascurrent position of the GNSS receiver 110 a GNSS time, satellite orbitdata (ephemeris) and satellite clock data. Accordingly, the time delayat which a punctual signal, should be centered may be calculated fromthe navigation solution and the punctual correlator tap may be placed atthe right timing location. In an exemplary embodiment of the invention,only one single tap correlator 320 may be utilized for each sniffchannel circuit 302 since knowledge of the location of the satellitesignals can be determined or derived based on the navigation solution.Accordingly, for each of the sniff channel circuits 302, there is noneed to search for satellite signals as with the regular channelcircuits 301

In operation, the regular channel circuit 301 may comprise a pluralityof multi-tap correlators 310 a, 310 b. The multi-tap correlator 310 amay be operable to perform correlation function of the regular channelcircuit 301 for generating GNSS measurements. The multi-tap correlator310 a may employ the DLL 312 a and utilize an early correlator tap and alate correlator tap to drive the DLL 312 a for producing a punctualcorrelator tap. The produced punctual correlator tap may be used to lockand/or track a visible GNSS satellite 120 a for generating GNSSmeasurements.

The sniff channel circuit 302 may comprise a single-tap correlator 320.The single-tap correlator 320 may be operable to correlate GNSS signalsfor the sniff channel circuit 302 to enable monitoring and/or detectingpower levels of available GNSS satellites 120. The single-tap correlator320 does not employ a DLL. A navigation solution of the GNSS receiver110 a, which provides information such as current position of the GNSSreceiver 110 a, GNSS time, satellite orbit data (ephemeris) andsatellite clock data, may be utilized by the single-tap correlator 320to produce a single punctual correlator tap. The timing location of thepunctual correlator tap may be guided by the navigation solution of theGNSS receiver 110 a. The time delay at which a punctual signal should becentered may be calculated from the navigation solution and the punctualcorrelator tap may be placed at the right timing location.

FIG. 4 is a flow chart illustrating exemplary steps for utilizingreduced functionality processing channels in a GNSS receiver, inaccordance with an embodiment of the invention. Referring to FIG. 4, theexemplary steps start at step 401. In step 402, one or more regularchannel circuits 204 in the GNSS receiver 200 may be utilized togenerate GNSS measurements for calculating a navigation solution intime. In step 403, one or more sniff channel circuits 206 in the GNSSreceiver 200 may be utilized to monitor power levels of currentlyvisible GNSS satellites 120 b, 120 c which are not being utilized by theregular channel circuits 204. In step 404, the GNSS receiver 200 maylose lock on one of currently tracked GNSS satellites 120 a which isbeing utilized by one of the regular channel circuits 204. In step 405,the GNSS receiver 200 may be operable to select an alternative GNSSsatellite 120 b from the currently monitored GNSS satellites 120 b, 120c based on the monitored power levels of the currently monitored GNSSsatellites 120 b, 120 c. In step 406, one of the regular channelcircuits 204 in the GNSS receiver 200 may be utilized to process GNSSsignals received from the selected alternative GNSS satellite 120 b. Theexemplary steps may proceed to the end step 407.

In various embodiments of the invention, a GNSS receiver 110 a, whichcomprises one or more regular channel circuits 204 and one or more sniffchannel circuits 206, may be operable to monitor power levels ofcurrently visible GNSS satellites 120 b, 120 c utilizing one or more ofthe sniff channel circuits 206. In this regard, the currently monitoredvisible GNSS satellites 120 b, 120 c are not being utilized by theregular channel circuits 204. The GNSS receiver 110 a may comprise, forexample, a GPS receiver, a GLONASS receiver, a Galileo receiver and/or aCompass receiver. An alternative GNSS satellite 120 b from the currentlymonitored GNSS satellites 120 b, 120 c may be selected by the GNSSreceiver 110 a based on the monitored power levels. GNSS signalsreceived from the selected alternative GNSS satellite 120 b may beprocessed by the GNSS receiver 110 a utilizing one of the regularchannel circuits 204. In this regard, the GNSS receiver 110 a may beoperable to detect, for example, SNRs or C/N0s of the currently visibleGNSS satellites 120 b, 120 c utilizing the sniff channel circuits 206.Each of the regular channel circuits 204 may be utilized to generateGNSS measurements for calculating a navigation solution of the GNSSreceiver 110 a. Each of the regular channel circuits 301 may comprise aplurality of multi-tap correlators 310 a, 310 b and each of themulti-tap correlators 310 a, may comprise a DLL 312 a. An earlycorrelator tap, a late correlator tap and the DLL 312 a may be utilizedby the multi-tap correlators 310 a to produce a punctual correlator tapduring a correlation, process.

Each of the sniff channel circuits 206 may not be utilized to generateGNSS measurements so that functionality of each of the sniff channelcircuits 206 may be reduced. Each of the sniff channel circuits 302 maycomprise a single-tap correlator 320. A navigation solution of the GNSSreceiver 110 a may be utilized by the single-tap correlator 320 toproduce a punctual correlator tap during a correlation process.

Another embodiment of the invention may provide a machine and/orcomputer readable storage and/or medium, having stored thereon, amachine code and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for utilizingreduced functionality processing channel in a GNSS receiver.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputer system or in a distributed fashion where different elements arespread across several interconnected computer systems. Any kind ofcomputer system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computer system with a computerprogram that, when being loaded and executed, controls the computersystem such that it carries out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform, a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method of communication using a globalnavigation satellite system (GNSS) receiver, comprising: generating aGNSS measurement utilizing a regular channel circuit; monitoringattributes of a plurality of GNSS satellites using a sniff channelcircuit having reduced functionality with respect to the regular channelcircuit; selecting an alternative GNSS satellite from the plurality ofGNSS satellites based on its monitored attribute; and processing asignal received from the selected alternative GNSS satellite utilizingthe regular channel circuit.
 2. The method of claim 1, wherein theplurality of GNSS satellites comprises visible GNSS satellites that arenot being used by the regular channel circuit.
 3. The method of claim 1,further comprising detecting a loss of a lock on a GNSS satellitecurrently tracked by the regular channel circuit.
 4. The method of claim3, wherein selecting an alternative GNSS satellite is performed inresponse to detecting the loss of the lock.
 5. The method of claim 1,wherein monitoring attributes comprises at least one of monitoring powerlevels, monitoring signal-to-noise ratios, and monitoringcarrier-to-noise density ratios.
 6. The method of claim 1, wherein theprocessing comprises generating GNSS measurements for calculating anavigation solution.
 7. The method of claim 1, further comprisinggenerating a second GNSS measurement utilizing a second regular channelcircuit.
 8. The method of claim 1, wherein a second sniff channelcircuit is also used to monitor attributes of the plurality of GNSSsatellites.
 9. The method of claim 1, wherein the regular channelcircuit comprises a multi-tap correlator.
 10. The method of claim 1,wherein the sniff channel circuit comprises a single-tap correlator. 11.A global navigation satellite system (GNSS) receiver, comprising: aregular channel circuit configured to generate a GNSS measurement; asniff channel circuit configured to monitor attributes of a plurality ofGNSS satellites, wherein the sniff channel circuit has reducedfunctionality with respect to the regular channel circuit; and abaseband processor configured to select an alternative GNSS satellitefrom the plurality of GNSS satellites based on its monitored attribute,wherein the regular channel circuit is further configured to process asignal received from the selected alternative GNSS satellite.
 12. Thereceiver of claim 11, wherein the sniff channel circuit is configured tomonitor the attributes of the plurality of GNSS satellites by monitoringvisible GNSS satellites that are not being used by the regular channelcircuit.
 13. The receiver of claim 11, wherein the regular channelcircuit is further configured to detect a loss of a lock on a GNSSsatellite it is currently tracking.
 14. The receiver of claim 13,wherein the baseband processor is further configured to select thealternative GNSS satellite in response to detecting the loss of thelock.
 15. The receiver of claim 11, wherein the sniff channel circuit isconfigured to monitor attributes by monitoring at least one of powerlevels, signal-to-noise ratios, and carrier-to-noise density ratios. 16.The receiver of claim 11, wherein the regular channel circuit isconfigured process the signal received from the alternative GNSSsatellite by generating GNSS measurements for calculating a navigationsolution.
 17. The receiver of claim 11, further comprising a secondregular channel circuit configured to generate a second GNSSmeasurement.
 18. The receiver of claim 11, further comprising a secondsniff channel circuit configured to monitor attributes of the pluralityof GNSS satellites.
 19. The receiver of claim 11, wherein the regularchannel circuit comprises a multi-tap correlator.
 20. The receiver ofclaim 11, wherein the sniff channel circuit comprises a single-tapcorrelator.